The Anié unit, located in central Togo, belongs to the suture zone of the Pan-African Dahomeyide belt. The aim of this work is to contribute to the updating of geological data focused on the lithostructural organization, petrography, and geochemistry of the rocks in this unit. The methodology used is based on a synthesis of previous work, geological mapping coupled with structural analysis, a petrographic study of thin sections, and a geochemical study using geotectonic discrimination diagrams. The results obtained show that the Anié unit is composed of granulites tectonically encased in gneisses. These granulites have a mineralogy of plagioclase, clinopyroxene, amphibole, biotite, and quartz. This paragenesis reflects a metamorphic evolution from granulitization to retromorphosis in the amphibolite facies. Geochemical data show that the rocks of the Anié unit are metaluminous. They have a calc-alkaline affinity and are more enriched in LREE than in HREE. Negative anomalies in Nb-Ta and Zr indicate magma from subduction zones. These rocks derive from an OIB (oceanic island basalts) type mantle source, which was modified in a subduction context associated with the nappes emplacement.
KeywordsGeologyInselbergsAniéDahomeyideTogo
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